Researchers from the Helmholtz Centre Berlin, in collaboration with institutions from Dresden, St. Andrews, La Plata, and Oxford, have definitively observed magnetic monopoles in a single crystal of Dysprosium Titanate. This groundbreaking discovery, published in the journal Science on September 3, demonstrates the emergence of monopoles through a neutron scattering experiment. The study reveals that the magnetic moments within the material reorganize into a structure termed "Spin-Spaghetti," facilitating the visibility of monopoles at temperatures between 0.6 to 2 Kelvin when influenced by an applied magnetic field.
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Researchers from the Helmholtz Centre Berlin, in cooperation with colleagues from Dresden, St. Andrews, La Plata and Oxford, have for the first time observed magnetic monopoles and how they emerge in a real material. They publish this result in the journal Science within the Science Express website on Sept. 3
Jonathan Morris, Alan Tennant and colleagues (HZB) undertook a neutron scattering experiment at the Berlin research reactor. The material under investigation was a single crystal of Dysprosium Titanate. This material crystallises in a quite remarkable geometry, the so called pyrochlore-lattice. With the help of neutron scattering Morris and Tennant show that the magnetic moments inside the material had reorganised into so-called „Spin-Spaghetti". This name comes from the ordering of the dipoles themselves, such that a network of contorted tubes (Strings) develops, through which magnetic flux is transported. These can be made visible by their interaction with the neutrons which themselves carry a magnetic moment. Thus the neutrons scatter as a reciprocal representation of the Strings.
During the neutron scattering measurements a magnetic field was applied to the crystal by the researchers. With this field they could influence the symmetry and orientation of the strings. Thereby it was possible to reduce the density of the string networks and promote the monopole dissociation. As a result, at temperatures from 0.6 to 2 Kelvin, the strings are visible and have magnetic monopoles at their ends.